Code review comment for lp://staging/~dimitern/juju-core/027-state-supports-nonced-provisioning

Reviewers: mp+157853_code.launchpad.net,

Message:
Please take a look.

Description:
state: add nonced provisioning support

Next step in nonced provisioning; adding support
in state: machine.SetInstanceId() renamed to
SetProvisioned(), taking instance id and nonce.
It allows you change it only once, so some tests
that assumed too much had to be changed (e.g.
changing instance id several times just to
trigger a machine change). Also CheckProvisioned()
is added to machine, taking a nonce and returning
bool, error; true is returned only when the
instance id is set and the nonce matches.

In the upcoming CL we'll bring everything
together - PA generating an unique nonce,
and checking it.

https://code.launchpad.net/~dimitern/juju-core/027-state-supports-nonced-provisioning/+merge/157853

(do not edit description out of merge proposal)

Please review this at https://codereview.appspot.com/8561044/

Affected files:
   A [revision details]
   M cmd/juju/ssh_test.go
   M cmd/juju/status_test.go
   M state/apiserver/api_test.go
   M state/machine.go
   M state/machine_test.go
   M state/megawatcher_internal_test.go
   M state/state.go
   M state/state_test.go
   M state/unit_test.go
   M worker/deployer/deployer_test.go
   M worker/firewaller/firewaller_test.go
   M worker/provisioner/provisioner.go
   M worker/uniter/filter_test.go
   M worker/uniter/uniter_test.go